"In some of the military contexts described by the Romans the Caledonians were the southern Picts centered on Strathmore and the Angus glens, with occasional shifts [mainly by a stroke of Ptolemy's pen] into the Highland massif to the east of the Great Glen"

Surely the confederation of tribes which merged into the northern Picts were centred on the Caledonians or Caledones of Roman times. The southern Picts were further south in the Perthshire and Fife area and were thought to be centred on the Venicones of Roman times. The southern Pictish confederation for a while seem to carry the name Maetea (spelling)